Replicated variable doesn't change

I have a problem with replicating object variable between players using dedicated server. I created an actor which is replicated as well as his boolean variable. The custom event toggling between values is set to multicast, but the custom event in player class that invokes the previous one is an RPC set to Run on Server. However, when I invoke player’s custom event with button press, I get those warnings on server log:
LogNet: Warning: ReadFieldHeaderAndPayload: GetFromIndex failed Object: FirstPersonCharacter_C
LogNet: Warning: ReceivedBunch: FieldCache == nullptr: FirstPersonCharacter_C
Both players are visible to each other on game start but communication with server seem to lack something. Does someone know what can be cause of this?
Any help is much appreciated

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